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首页> 外文期刊>The astronomical journal >Rotation of Low-mass Stars in Upper Scorpius and ρ Ophiuchus with K2
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Rotation of Low-mass Stars in Upper Scorpius and ρ Ophiuchus with K2

机译：K2使上天蝎座和蛇夫座中的低质量恒星自转

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We present an analysis of K2 light curves (LCs) for candidate members of the young Upper Sco (USco) association (～8 Myr) and the neighboring ρ Oph embedded cluster (～1 Myr). We establish ～1300 stars as probable members, ～80% of which are periodic. The phased LCs have a variety of shapes which can be attributed to physical causes ranging from stellar pulsation and stellar rotation to disk-related phenomena. We identify and discuss a number of observed behaviors. The periods are ～0.2–30 days with a peak near 2 days and the rapid period end nearing breakup velocity. M stars in the young USco region rotate systematically faster than GK stars, a pattern also present in K2 data for the older Pleiades and Praesepe systems. At higher masses (types FGK), the well-defined period–color relationship for slowly rotating stars seen in the Pleiades and Praesepe systems is not yet present in USco. Circumstellar disks are present predominantly among the more slowly rotating M stars in USco, with few disks in the subday rotators. However, M dwarfs with disks rotate faster on average than FGK systems with disks. For four of these disked M dwarfs, we provide direct evidence for disk locking based on the K2 LC morphologies. Our preliminary analysis shows a relatively mass-independent spin-up by a factor of ～3.5 between USco and the Pleiades, then mass-dependent spin-down between Pleiades and Praesepe.
机译：我们对年轻的上斯科（USco）协会（〜8 Myr）和邻近的ρOph嵌入星团（〜1 Myr）的候选成员的K2光曲线（LC）进行了分析。我们建立了约1300个恒星，其中约80％是周期性的。相控LC具有多种形状，可以归因于物理原因，从恒星脉动和恒星旋转到磁盘相关现象。我们确定并讨论了许多观察到的行为。周期为〜0.2-30天，在2天左右达到峰值，快速期结束于接近解体速度。在年轻的USco地区，M星的系统旋转速度比GK星的系统快，这也适用于较老的P宿星和Praesepe系统的K2数据。在较高质量（FGK类型）下，USco尚不存在在the宿星系和Praesepe系统中看到的缓慢旋转恒星的明确的周期-颜色关系。在USco中旋转较慢的M恒星中主要存在星际盘，次日轮中则很少有盘。但是，带有磁盘的M个矮星的平均旋转速度要高于带有磁盘的FGK系统。对于这四个磁盘状M矮星，我们提供了基于K2 LC形态的磁盘锁定的直接证据。我们的初步分析显示，在USco和le宿星之间，相对质量无关的旋转降低了〜3.5倍，然后在le宿星和Praesepe之间发生了质量相关的旋转降低。

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